The card is slower in syncing to the A1200 motherboard, because it runs async to the A1200. This takes some time, as you can see on the Bustest screenshot. This may or may not make flaky motherboards more compatible - tests in the field will have to show this. Don't expect too much - there are lots of boards out there that have true assembly errors, and I have described how to fix them. Also, many instability problems are caused by the power supply, and a new accelerator can't do wonders if the +5V line has ripple.